JP3702551B2 - Broadcast receiving system and broadcast receiving method using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a broadcast receiving system that receives two types of broadcast radio waves, and in particular, broadcast reception that individually receives FM radio broadcast and FM multiplex broadcast that displays traffic information on a monitor on which a road map is displayed. The present invention relates to a system and a broadcast receiving method using the system.
[0002]
[Prior art]
In a system in which the FM multiplex receiver and FM radio apparatus are composed of two tuners, the basic functional elements of the FM multiplex receiver 1 and the FM radio apparatus 2 are provided independently of each other as shown in FIG. Yes. Therefore, there is no correlation between the channel selection frequency (multiplex reception frequency) f0 of the FM multiplex receiver 1 and the channel selection frequency (radio frequency) f1 of the FM radio device 2.
[0003]
By the way, in general, in a superheterodyne receiver, although it is a very small amount, local oscillation when a certain reception frequency is selected is radiated as noise radio waves from an antenna or the like.
[0004]
Here, for example, in FIG. 6, the intermediate frequency of the FM multiplex receiver is fIF, and the relationship between the multiplex reception frequency f0 and the radio frequency f1 is
f0−fIF = f1
If the electric field strength from the FM radio broadcasting station is weak, it overlaps with the leakage of the local oscillation frequency (f0-fIF) from the antenna of the FM multiplex receiver 1, and noise is generated in the sound of the FM radio device 2. Will be mixed.
[0005]
In order to alleviate such a problem, conventionally, leakage of local oscillation from the FM multiplex receiver 1 is achieved by inserting an isolation buffer 3 between the FM multiplex receiver 1 and the FM multiplex antenna as shown in FIG. Is attenuated, and the influence on the FM radio apparatus 2 is reduced.
[0006]
[Problems to be solved by the invention]
By adding the isolation buffer 3 as described above and attenuating the noise in the opposite direction to normal, for example, when the level of local leakage from the FM multiplex receiver 1 is −60 dBm, the isolation buffer 3 is isolated. Is 40 dB, the radiation noise from the antenna is suppressed to -100 dBm or less, and the FM radio apparatus 2 is hardly affected.
[0007]
However, if the isolation buffer 3 is added externally, the system becomes complicated, and even if the isolation buffer 3 is inserted in the FM multiplex receiver 1, the size of the receiver is similarly increased.
[0008]
Accordingly, an object of the present invention is to provide a broadcast receiving system and a broadcast receiving method using the same, in which noise due to leakage of local oscillation does not affect the FM radio without adding an isolation buffer. is there.
[0009]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a first superheterodyne broadcast receiving apparatus that receives a first broadcast radio wave and demodulates it using an intermediate frequency, and a second broadcast radio wave receiving second broadcast radio wave. And a control unit that controls the first broadcast receiving device and the second broadcast receiving device, and the control unit determines whether or not the second broadcast receiving device is ON. If the second broadcast receiving apparatus is ON, the first broadcast receiving apparatus is selected so that the channel selection frequency of the first broadcast receiving apparatus is not set to a predetermined prohibited frequency. It has a function to control the station operation.
[0010]
In the first broadcast receiving device, the control unit is configured to cause a first adverse effect on the second broadcast radio wave reception of the second broadcast reception device due to local oscillation at the time of receiving the first broadcast radio wave. Storage means for storing a broadcast channel selection frequency as a forbidden frequency, determination means for determining whether or not the second broadcast reception apparatus is ON, and the second broadcast reception apparatus is ON by the determination means Control the channel selection operation of the first broadcast receiving device so that the channel selection frequency of the first broadcast receiving device is not set to the prohibited frequency stored in the storage means Multiple channel selection control means.
[0011]
Specifically, the first broadcast receiving apparatus is an FM multiplex receiving apparatus that receives FM multiplex broadcast radio waves including traffic information, and the second broadcast receiving apparatus is a radio apparatus that receives at least FM radio broadcast radio waves. It is.
[0012]
When receiving a broadcast, it is first determined whether or not the second broadcast receiving device is ON. If it is determined that the second broadcast receiving device is ON, the selection of the first broadcast receiving device is performed. While changing the station frequency, it is determined whether or not the channel selection frequency is the same as the prohibited frequency stored in the storage means. Then, when the channel selection frequency is the same as the prohibited frequency stored in the storage unit, a change in the channel selection frequency is continued after adding or subtracting a predetermined frequency change amount to the channel selection frequency.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
<Configuration>
FIG. 1 is a block diagram showing an entire broadcast receiving system according to an embodiment of the present invention. As shown in FIG. 1, the broadcast receiving system includes a main control unit 13 (control unit) between an FM multiplex receiving device 11 serving as a first broadcast receiving device and an FM radio device 12 serving as a second broadcast receiving device. Are connected by buses 14a and 14b, and the channel selection status of the FM radio apparatus 12 is recognized by the main control unit 13 and the FM multiplex receiver 11, and the intermediate frequency fIF of the FM multiplex receiver 11 is determined from the channel selection frequency f1 of the FM radio apparatus 12. Therefore, the FM multiplex receiver 11 does not select a signal having a frequency as high as possible.
[0014]
The FM multiplex receiver 11 includes an FM front end 22 that receives an FM multiplex broadcast radio wave received by an antenna 21, an IF circuit 23 that detects an FM multiplex signal converted into an IF signal by the FM front end 22, and a post-detection Of the received signal by extracting only the FM multiplex signal from the received signal, the multiplex filter circuit 24 for determining the presence of the signal from the FM multiplex broadcast station, and error-correcting and demodulating the extracted FM multiplex signal into the signal. A signal processing circuit 25 for extracting packet data contained therein, a descrambling circuit 26 for releasing the scrambling of the packet data, a transmission / reception circuit 27 for transmitting / receiving signals to / from the bus 14a, and a ROM 28 and a RAM 29 are connected. CPU 30 for processing signals from descrambling circuit 26 and transmission / reception circuit 27, and CP And a PLL circuit 31 for controlling the reception frequency with the FM front end 22 based on a command from 30.
[0015]
The FM radio apparatus 12 includes an FM front end 42 that receives an FM radio broadcast wave received by an antenna 41, an IF circuit 43 that detects an FM radio signal converted into an IF signal by the FM front end 42, and a post-detection Stereo demodulation circuit 44 that extracts an FM stereo signal from the signal, AF amplification circuits 45a and 45b that amplify each of the L signal and the R signal of the extracted FM stereo signal, and each amplified signal that is output as an audio signal A signal is transmitted / received between the L speaker 46a and the R speaker 46b and the bus 14b, and a signal received from the operation unit 47 of the front panel of the vehicle connected to the ROM 49 and the RAM 50 is processed. In addition, the CPU 5 transmits predetermined information such as a reception frequency to the display unit 53 for display. When, and a PLL circuit 52 for controlling the reception frequency with the FM front end 42 based on a command from CPU 51.
[0016]
The main control unit 13 controls the entire broadcast receiving system. The main control unit 13 is used to input travel position detection means 61 for detecting the travel position of the vehicle, various commands for car navigation, and necessary data. An operation unit 62 is connected to a display unit 63 for displaying a road map and traffic information to the driver, and signals are transmitted between the FM multiplex receiver 11 and the FM radio unit 12 through the buses 14a and 14b. The FM multiplex receiving device 11 and the FM radio device 12 are connected to a storage means composed of a ROM 65 and a RAM 66 and process various signals received from the transmitting / receiving circuits 64a and 64b and the operation unit 62. A CPU 67 that controls and displays signals relating to road maps and traffic information to the display unit 63 and displays them. Provided.
[0017]
Here, the CPU 67 outputs navigation information and the like to the display unit 63 and manages the integrated control of the FM multiplex receiver 11 and the FM radio device 12, and is stored in the ROM 65 and the RAM 66 as shown in FIG. The travel position detected by the travel position detection means 61 is recognized on the map, and if there is traffic information such as traffic jam information in the FM multiplexed signal from the first transmission / reception circuit 64a based on the signal from the operation unit 62, this A travel position control means 71 that outputs predetermined navigation information and the like, a determination means 72 that determines whether the FM radio apparatus 12 is ON based on a signal from the second transmission / reception circuit 64b, When the judging means 72 judges that the FM radio apparatus 12 is ON, the channel selection frequency of the FM multiplex receiving apparatus 11 is stored in the ROM 65 or the RAM 66. And and a prohibition frequency fx multiplex tuning controller 73 for controlling the tuning operation of the FM multiplex receiver apparatus so as not to be set to (= f0 + fIF). The operation of the CPU 67 of the main control unit 13 will be described in detail below.
[0018]
<Operation>
The operation of the broadcast receiving system having the above configuration will be described. When the vehicle is traveling, the driver or the like receives FM multiplex broadcast radio waves by the FM multiplex receiver 11, and the main control unit 13 determines the travel position detected by the travel position detection means 61 on a predetermined map. While recognizing, if there is traffic information such as traffic jam information in the FM multiplex signal from the first transmission / reception circuit 64a, it takes it and outputs predetermined navigation information and the like. In this case, driving is often performed while simultaneously receiving FM radio.
[0019]
By the way, generally, when the electric field strength of an FM radio broadcasting station is low, the following two types of noise mixing (1) and (2) often occur in the FM radio apparatus 12.
[0020]
(1) When the FM multiplex receiver 11 selects a channel in the auto scan mode, noise occurs in the FM radio broadcast when the auto scan frequency passes the frequency f1 + fIF.
[0021]
(2) When the FM multiplex receiver 11 is selected in the manual mode, the relationship between the channel selection frequencies of the FM radio device 12 and the FM multiplex receiver 11 is
f1 = f0−fIF
If this is the case, noise is always added to the sound of the FM radio apparatus 12.
[0022]
FIG. 3 is a diagram illustrating the channel selection operation of the FM multiplex receiver 11 and the FM radio device 12, in which (a) is the channel selection operation of the FM radio device 12, and (b) is the channel selection operation of the FM multiplex receiver 11. Is the action.
[0023]
As an example, as shown in FIG. 3, when the upper limit frequency of FM radio broadcasting and FM multiplex broadcasting is fL and the lower limit frequency is fH, for example, in Japan, fL = 76 MHz and fH = 90 MHz.
fL ≦ f0 ≦ fH
It becomes. Further, the stepwise change amount of frequency for channel selection (hereinafter referred to as “channel selection step”) Δf is assumed to be 0.1 MHz, and further, an intermediate frequency as a bandwidth from channel selection frequency f0 to prohibited frequency fx. It is assumed that fIF is 10.7 MHz. in this case,
fx = f0 + fIF
Therefore, if this forbidden frequency fx exceeds fH, that is, if it comes out of the broadcast band, it will not be disturbed.
[0024]
this is,
Reception frequency-Local oscillation frequency = Intermediate frequency (= 10.7MHz fixed)
In this case, the forbidden frequency fx = f0 + fIF.
Local oscillation frequency-reception frequency = intermediate frequency (= 10.7MHz fixed)
When the FM multiplex receiver 11 is manufactured so as to satisfy the relationship, the forbidden frequency fx = f0−fIF. In this case, there is a possibility that the FM radio reception frequency f0 and the prohibited frequency fx match. Specifically, there is a problem that noise occurs in both the auto scan mode and the manual mode.
[0025]
Therefore, in order to prevent the occurrence of noise in both the auto scan mode and the manual mode, reception is performed according to the procedure of the flowcharts of FIGS.
[0026]
First, in the vehicle, when the driver or the like operates the operation unit 62 to turn on the car navigation function, the main control unit 13 sets the FM multiplex receiver 11 to ON. In step S1, the CPU 67 in the main control unit 13 determines whether or not the function of the FM radio apparatus 12 is turned on by the judging means 72. Since there is no need to consider the influence, the forbidden frequency fx of the FM multiplex receiver 11 is reset in step S2.
[0027]
If it is determined in step S1 that the FM radio apparatus 12 is ON, it is determined in step S3 whether or not the FM radio apparatus 12 is in the auto scan mode. If the auto scan mode is not set, that is, the manual mode is selected, the process skips to step S7 to obtain the channel selection frequency f0 from the FM radio apparatus 12, and the forbidden frequency fx of the FM multiplex reception apparatus 11 is calculated based on the following equation in step S8. To calculate.
[0028]
fx = f0 + fIF = f0 + 10.7 MHz
Thereafter, in step S9, it is determined whether or not the prohibition frequency fx exceeds the upper limit frequency fH. If it exceeds, the prohibition frequency fx of the FM multiplex receiver 11 is reset in step S2.
[0029]
On the other hand, if it is determined in step S3 that the FM radio device 12 is in the auto scan mode, the FM multiplex receiver 11 stops its function until the scanning operation of the FM radio device 12 is completed (step S4). After the scanning operation of the FM radio apparatus 12 is completed (step S5), the function of the FM multiplex receiving apparatus 11 is resumed (step S6). Then, the prohibited frequency fx is defined as in steps S7 to S9 described above.
[0030]
Thereafter, the channel selection operation of the FM multiplex receiver 11 starts. Here, first, after obtaining the tuning frequency fm in step S10, it is determined whether or not the tuning frequency fm is the prohibited frequency fx (step S11).
[0031]
When it is determined that the channel selection frequency fm is equal to the prohibited frequency fx, the processing from Step S12 to Step S15 described later is omitted and the processing from Step S16 is performed. If it is determined in step S11 that the channel selection frequency fm does not coincide with the prohibited frequency fx, it is determined in step S12 whether or not FM multiplexing information exists, and FM multiplexing information exists. If it is determined, the FM multiplexed information is received and then displayed on the display unit 63 in step S13. On the other hand, if it is determined in step S12 that FM multiplex information does not exist, the multiple channel selection control means 73 calculates the frequency f1 (= fm + Δf) to be selected next (step S14), and this f1 is prohibited. It is determined whether or not the frequency is fx (step S15). When f1 = fx, Δf is further added to f1 to recalculate f1 avoiding the forbidden frequency fx (step S16), and information about this frequency f1 is transmitted to the FM multiplex receiver 11 through the transmission / reception circuits 64a and 27. It is given to CPU30. In step S17, the CPU 30 determines whether or not this f1 exceeds the upper limit frequency fH. If it is determined that it does not exceed the upper limit frequency fH, tuning is performed according to f1 calculated in step S18. On the other hand, if it is determined in step S17 that f1 has exceeded the upper limit frequency fH, the lower limit frequency fL is adopted as the channel selection frequency (step S19).
[0032]
In this way, when there is a possibility that noise is mixed in the FM radio apparatus 12, the isolation buffer is not selected for the FM multiplex receiving apparatus 11, so that the isolation buffer can be reduced as in the conventional example. Even if it is not added, it is possible to easily take measures against local oscillation, and to prevent an increase in the size of the system.
[0033]
In the above embodiment, the channel selection operation of the FM multiplex receiver 11 continues incrementing the frequency by continuously adding the predetermined change amount Δf from the upper limit frequency fL, but conversely the predetermined change from the lower limit frequency fH. The frequency may be decremented by continuing to subtract the amount Δf, and at that time, the channel selection may be performed while avoiding the forbidden frequency fx.
[0034]
In the above example, only the FM radio apparatus is described as an example of the radio apparatus. However, it is needless to say that an apparatus with an AM radio function may be used.
[0035]
【The invention's effect】
According to the present invention, it is determined whether or not the second broadcast receiving apparatus is ON, and when the second broadcast receiving apparatus is ON, the channel selection frequency of the first broadcast receiving apparatus is a predetermined value. Since the channel selection operation of the first broadcast receiving apparatus is controlled so as not to be set to the forbidden frequency, the frequency that adversely affects the second broadcast receiving apparatus among the local oscillations from the first broadcast receiving apparatus Generation of radio waves in the band can be reliably prevented, and mixing of radio noise into the second broadcast receiving apparatus can be prevented. In particular, since there is no need to install an isolation buffer on the first broadcast receiving apparatus side as in the prior art, there is an effect that an increase in size of the broadcast receiving system can be prevented.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an entire broadcast receiving system according to an embodiment of the present invention.
FIG. 2 is a block diagram mainly showing an internal configuration of a navigation system main body of the broadcast receiving system according to the embodiment of the present invention.
FIG. 3 is a diagram illustrating a channel selection operation of a multiplex reception device and a radio device in the broadcast reception system of one embodiment of the present invention.
FIG. 4 is a flowchart showing the operation of the broadcast receiving system according to the embodiment of the present invention.
FIG. 5 is a flowchart showing the operation of the broadcast receiving system according to the embodiment of the present invention.
FIG. 6 is a principle diagram showing a conventional broadcast receiving system.
FIG. 7 is a principle diagram showing a conventional broadcast receiving system.
[Explanation of symbols]
11 FM multiplex receiver 12 FM radio device 13 Main control unit 14a, 14b Bus 61 Traveling position detecting means 62 Operation unit 63 Display unit 64a, 64b Transmission / reception circuit 65 ROM
66 RAM
67 CPU
71 Traveling position control means 72 Judgment means 73 Multiple channel selection control means

Claims (4)

A first broadcast receiver of a superheterodyne system that receives a first broadcast radio wave and demodulates using an intermediate frequency ;
A second broadcast receiving device for receiving a second broadcast radio wave;
A control unit for controlling the first broadcast receiving device and the second broadcast receiving device,
The control unit determines whether or not the second broadcast receiving device is ON, and when the second broadcast receiving device is ON, the tuning frequency of the first broadcast receiving device is a predetermined frequency. A broadcast receiving system having a function of controlling a channel selection operation of the first broadcast receiving apparatus so as not to be set to a prohibited frequency. The broadcast receiving system according to claim 1,
The controller is
In the first broadcast receiving apparatus, the first broadcast tuning frequency when the second broadcast radio wave reception of the second broadcast receiving apparatus is adversely affected by local oscillation at the time of receiving the first broadcast radio wave is a prohibited frequency. Storage means for storing as,
Determining means for determining whether or not the second broadcast receiving apparatus is ON;
When the determination unit determines that the second broadcast receiving device is ON, the channel selection frequency of the first broadcast receiving device is not set to the prohibited frequency stored in the storage unit. As described above, a broadcast receiving system comprising: multiple channel selection control means for controlling the channel selection operation of the first broadcast receiving apparatus.   3. The broadcast receiving system according to claim 1, wherein the first broadcast receiving device is an FM multiplex receiving device that receives FM multiplex broadcasting radio waves including traffic information, and the second broadcast receiving device. A broadcast receiving system, wherein the apparatus is a radio apparatus that receives at least FM radio broadcast radio waves. A broadcast receiving method using the broadcast receiving system according to claim 1 or 2,
Determining whether the second broadcast receiver is ON;
When it is determined that the second broadcast receiving apparatus is ON, the tuning frequency of the first broadcast receiving apparatus is changed, and the tuning frequency is the same as the prohibited frequency stored in the storage unit. A step of determining whether or not
A step of adding or subtracting a predetermined frequency change amount to the channel selection frequency and continuing the change of the channel selection frequency when the channel selection frequency is the same as the prohibited frequency stored in the storage means; Broadcast receiving method provided.

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